Drag and drop
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#ifndef DRAGWIDGET_H
#define DRAGWIDGET_H
#include <QByteArray>
#include <QFrame>
#include <QString>
#include <QStringList>
class QComboBox;
class QFrame;
class QLabel;
class QTextBrowser;
class DragWidget : public QFrame
{
Q_OBJECT
public:
DragWidget(QWidget *parent);
void setData(const QString &mimetype, const QByteArray &newData);
signals:
void dragResult(const QString &actionText);
void mimeTypes(const QStringList &types);
protected:
void dragEnterEvent(QDragEnterEvent *event);
void dropEvent(QDropEvent *event);
void mouseMoveEvent(QMouseEvent *event);
void mousePressEvent(QMouseEvent *event);
private:
QByteArray data;
QLabel *dragDropLabel;
QPoint dragStartPosition;
QString mimeType;
};
#endif
#include <QtGui>
#include "dragwidget.h"
DragWidget::DragWidget(QWidget *parent)
: QFrame(parent)
{
setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
dragDropLabel = new QLabel("", this);
dragDropLabel->setAlignment(Qt::AlignHCenter);
QHBoxLayout *layout = new QHBoxLayout(this);
layout->addStretch(0);
layout->addWidget(dragDropLabel);
layout->addStretch(0);
setAcceptDrops(true);
}
// Accept all actions, but deal with them separately later.
void DragWidget::dragEnterEvent(QDragEnterEvent *event)
{
event->acceptProposedAction();
}
void DragWidget::dropEvent(QDropEvent *event)
{
if (event->source() == this && event->possibleActions() & Qt::MoveAction)
return;
if (event->proposedAction() == Qt::MoveAction) {
event->acceptProposedAction();
// Process the data from the event.
emit dragResult(tr("The data was moved here."));
} else if (event->proposedAction() == Qt::CopyAction) {
event->acceptProposedAction();
// Process the data from the event.
emit dragResult(tr("The data was copied here."));
} else {
// Ignore the drop.
return;
}
// End of quote
emit mimeTypes(event->mimeData()->formats());
setData(event->mimeData()->formats()[0],
event->mimeData()->data(event->mimeData()->formats()[0]));
}
void DragWidget::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
dragStartPosition = event->pos();
}
void DragWidget::mouseMoveEvent(QMouseEvent *event)
{
if (!(event->buttons() & Qt::LeftButton))
return;
if ((event->pos() - dragStartPosition).manhattanLength()
< QApplication::startDragDistance())
return;
QDrag *drag = new QDrag(this);
QMimeData *mimeData = new QMimeData;
mimeData->setData(mimeType, data);
drag->setMimeData(mimeData);
Qt::DropAction dropAction = drag->exec(Qt::CopyAction | Qt::MoveAction);
switch (dropAction) {
case Qt::CopyAction:
emit dragResult(tr("The text was copied."));
break;
case Qt::MoveAction:
emit dragResult(tr("The text was moved."));
break;
default:
emit dragResult(tr("Unknown action."));
break;
}
}
void DragWidget::setData(const QString &mimetype, const QByteArray &newData)
{
mimeType = mimetype;
data = QByteArray(newData);
dragDropLabel->setText(tr("%1 bytes").arg(data.size()));
QStringList formats;
formats << mimetype;
emit mimeTypes(formats);
}
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QPixmap>
#include <QPoint>
class QComboBox;
class QLabel;
class QLineEdit;
class QMouseEvent;
class QTextEdit;
class DragWidget;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
public slots:
void setDragResult(const QString &actionText);
void setMimeTypes(const QStringList &types);
private:
QComboBox *mimeTypeCombo;
DragWidget *dragWidget;
};
#endif
#include <QtGui>
#include "dragwidget.h"
#include "mainwindow.h"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
{
QFrame *centralWidget = new QFrame(this);
QLabel *mimeTypeLabel = new QLabel(tr("MIME types:"), centralWidget);
mimeTypeCombo = new QComboBox(centralWidget);
QLabel *dataLabel = new QLabel(tr("Amount of data (bytes):"), centralWidget);
dragWidget = new DragWidget(centralWidget);
connect(dragWidget, SIGNAL(mimeTypes(const QStringList &)),
this, SLOT(setMimeTypes(const QStringList &)));
connect(dragWidget, SIGNAL(dragResult(const QString &)),
this, SLOT(setDragResult(const QString &)));
QVBoxLayout *mainLayout = new QVBoxLayout(centralWidget);
mainLayout->addWidget(mimeTypeLabel);
mainLayout->addWidget(mimeTypeCombo);
mainLayout->addSpacing(32);
mainLayout->addWidget(dataLabel);
mainLayout->addWidget(dragWidget);
statusBar();
dragWidget->setData(QString("text/plain"), QByteArray("Hello world"));
setCentralWidget(centralWidget);
setWindowTitle(tr("Drag and Drop"));
}
void MainWindow::setDragResult(const QString &actionText)
{
statusBar()->showMessage(actionText);
}
void MainWindow::setMimeTypes(const QStringList &types)
{
mimeTypeCombo->clear();
mimeTypeCombo->addItems(types);
}
#include <QtGui>
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow *window1 = new MainWindow;
MainWindow *window2 = new MainWindow;
window1->show();
window2->show();
return app.exec();
}
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